1. Field of the Invention
This invention relates to an electrophotographic image forming apparatus, and more particularly to cleaning devices for removing residual toner and debris from a charge retentive surface of an image forming apparatus.
2. Description of Related Art
Typical cleaning methods in electrophotographic applications such as xerography, include a method to clean the charge retentive surface of an image forming apparatus by wiping with a fur brush, a web, a blade and the like, a method to clean by using magnetism or a magnetic brush, a method to clean by using an air current and/or a combination of at least several of the above. Cleaning methods employing an air current, either in combination with a brush, brush and blade or multiple blades are most preferred for use with the apparatus described herein.
The control of inlet air flow is essential for cleaning devices which use air flow through the cleaner housing. Cleaner housings may have upstream and downstream air inlets, such as electrostatic brush cleaners, for instance, and must balance the air flows from the two sides of the housing. This is typically done by controlling the cleaner housing spacing to the photoreceptor, the spacing between the brush and the cleaner housing inner wall and/or by adding interferences between the brush and the cleaner housing inner wall near the air inlet to create a pressure situation which will affect the air flow. All of these air flow control methods are effective to some degree.
Each, however, requires extremely close tolerances to maintain the spacings and interferences which are essential for the methods to function as desired. Further, there are generally a large number of parts which must be taken into account to determine the total tolerance stackup for the spacings and interferences. Some parts, such as the electrostatic brush, cannot be held to very tight tolerances and have poor environmental and age stability. Other parts, such as a cleaner housing assembly, can be manufactured to a moderate tolerance but, because other portions of the part must also be held to a critical location(s), the tolerance at the air inlet is compromised by the competing function(s). This problem may occur in many types of cleaner housings situated against the photoreceptor with active or passive air flow and used to control toner or other effluent emissions.
Additionally, toner emissions have been controlled on some blade cleaner housings by use of an upstream film seal riding on the photoreceptor surface. These seals prevent toner clouds, formed at the tip of the cleaning blade, from escaping the cleaner housing. No detrimental affects are caused by these film seals riding on a photoreceptor surface unless an untransferred toner image would be disturbed.